The report did not specify the financial terms of the deal.
The tech giant's plans for Emotient were not immediately clear, the Journal reported, confirming the news with an Apple spokeswoman.
Emotient's software reads the expressions of individuals and crowds to gain insights that can be used by advertisers to assess viewer reaction or a medical practitioner to better understand signs of pain in patients.
San Diego-based Emotient had previously raised $8 million from investors including Intel Capital, the Journal said.
Apple and Emotient did not immediately respond to requests for comment.
© Thomson Reuters 2016